CDC 6 (960) DTZS 
ICS 71.100.80 
© TBS 2022                                                                                               1st Edition 
  
  
 
 
Chemicals used for treatment of water intended for human 
consumption - Aluminium Sulfate. 
   
  
  
  
  
  
  
  
  
  
  
  
 
  
  
  
  
 
 
 
 
 
 
 
 
 
 
 
  
  
  
 
 
 
 
TANZANIA BUREAU OF STANDARDS   
                                                                                                 
 
 
 
 
   
  
  
 
DRAFT TANZANIA STANDARD  
  
CDC 6 (960) DTZS 
 
© TBS 2022                                                                                                1st Edition 
  
 Foreword  
  
This Draft Tanzania Standard is being developed by the Water Quality Technical Committee 
under supervision of the Chemical Division Standards Committee and it is in accordance with 
the procedures of the Bureau. 
  
This Tanzania Standard has been prepared with assistance drawn from:  
  
BS EN 878:2016 Chemicals used for treatment of water intended for human 
consumption - Aluminium Sulfate,  published by British Standards Institution.  
 
RS 353-1:2017 Chemicals used for treatment of water intended for human 
consumption - Aluminium Sulfate,  published by Rwanda Standards Board. 
 
ANSI/AWWA B403-09 Aluminum Sulfate - Liquid, Ground, or Lump,  published by 
American Water Works Association (AWWA)  
 
  
In reporting the result of a test or analysis made in accordance with this Tanzania Standard, if 
the final value, calculated or observed is to be rounded off, it shall be done in accordance with 
TZS 4 (see clause 2).  
  
  
  
  
  
  
  
  
  CDC 6 (960) DTZS 
 
© TBS – All rights reserved 
  
    
DRAFT TANZANIA STANDARD                    CDC 6 (960) DTZS 
  
Chemicals used for treatment of water intended for human consumption 
- Aluminium Sulfate.  
  
1 Scope  
 
This Draft Tanzania Standard specifies requirements, sampling, and tests method for 
Aluminium Sulfate used in coagulation of water intended for human consumption.  
 
2 Normative references  
  
The following referenced documents are indispensable for the application of this document. 
The latest edition of the referenced document (including any amendments) applies;  
 
TZS 4 Rounding off numerical values  
TZS 59 / ISO 3696 Water  for analytical laboratory use - Specification and test 
methods . 
TZS 1445, Sampling of chemical products for industrial use - Safety in sampling 
TZS 1444, Chemical products for industrial use - Sampling - Vocabulary 
 
  
3 Terms and definitions 
For the purposes of this document terms and definitions given in TZS 1444/ ISO 6206 and the 
following apply.  
ISO and IEC maintain terminological databases for use in standardization at the following 
addresses: 
— ISO Online browsing platform: available at http://www.iso.org/obp 
 
water intended for human consumption 
water either in its original state or after treatment, intended for drinking, cooking, food 
preparation or other domestic purposes, regardless of its origin and whether it is supplied 
from a distribution network, from a tanker, or in bottles or containers 
 
4 Requirements  
  
4.1 General requirements 
 
4.1.1 Descriptions   
4.1.1.1 Chemical name ; Aluminium Sulfate. 
4.1.1.2 Relative molecular mass ; 342.14 
4.1.1.3 Empirical  formula; Al2(SO4) 3.  
4.1.1.4 Chemical formula ; Al2(SO4) 3·n H2O 
  
4.1.2 Physical properties  
  
4.1.2.1 The product is a white solid or colourless to yellow clear liquid. 
4.1.2.2  
 
 CDC 6 (960) DTZS 
 
© TBS – All rights reserved 
 4.2 Specific requirements 
 
4.2.1 The material, when tested according to the methods prescribed in Annexes A, B, and C 
shall comply with the specific requirements given in Table 1. 
 
Table 1 Specific requirements for Aluminium Sulfate 
 
 
S/N  
Characteristic  
Requirement  
  
Method of 
test  
 
Solid   
Solution  
i.  Aluminium content (as AI 2O3), 
 percent by mass, min   
16  
8  
Annex A  
ii. Iron (as Fe), percent by mass, 
max 0.004  Annex B 
iii. Insoluble matter, percent by 
mass, max 0.5 0.2 Annex C 
iv. pH ( of 5 percent solution ), min 3 Annex D 
 
 
4.2.3 Toxic substances  
The content of toxic substances shall comply with the requirements specified in Table 2.  
  
Table 2 — Toxic substances  
 
Element   
Maximum limit mg/kg of product  
  
Arsenic (As)  14 
Cadmium (Cd)  3 
Chromium (Cr)  30 
Mercury (Hg)  4 
Nickel (Ni)  20 
Lead (Pb)  40 
Antimony (Sb)  20 
Selenium (Se)  20 
NOTE Cyanide (CN-) is usually not relevant because of the acidity of the product. 
Pesticides and polycyclic aromatic hydrocarbons are not relevant since the raw materials 
used in the manufacturing process are free of them. For maximum impact of these 
products on trace metal content in drinking water see A.2. 
 
 
5 Packing and marking  
  
5.1 Packaging  
  
Aluminium Sulfate shall be packed in clean, dry and tight containers, without faults, made of 
material which do not affect the contents. 
In order that purity of the product is not affected, the means of delivery shall not have been 
used previously for any different product or it shall have been specially cleaned and prepared 
before use.  
 
 
 
 
 
  CDC 6 (960) DTZS 
 
 
© TBS – All rights reserved 
 5.2 Marking  
The following information shall be marked legibly and indelibly on the container;  
 
a) name and formula of the product as ‘ALUMINIUM SULFATE’ (Al 2(SO4) 3·n H2O or 
Al2(SO4) 3)  
b) the name and address of manufacturer.  
c) net content.  
d) batch or code number.  
e) available Aluminium content.  
f) dates of manufacture and best before.  
g) instruction for handling, storage and use,  
h) first aid instructions. 
i) the words ‘STORE IN COOL AND DRY PLACE AWAY FROM DIRECT SUNLIGHT’ 
j) hazard warning in symbol or words   
 
6 Sampling   
Sampling of Aluminium Sulfate shall be done as per TZS 1443/ISO 8213 while observing the 
general recommendations as given in TZS 1445/ISO 3165 and TZS 1444/ISO 6206 
 
7 Testing  
Methods of tests for Aluminium Sulfate shall be as prescribed in the Annexes.  
  
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 CDC 6 (960) DTZS 
 
© TBS – All rights reserved 
 Annex A  
(Normative)   
Determination of Aluminium content. 
A-1 General 
Two methods are prescribed, namely (a) gravimetric method and (b) titration with EDTA 
solution. Gravimetric method shall be used, as referee method in case of dispute. 
A-2 Method A (Gravimetric Method) 
A-2.1 Reagents 
A-2.1.1 Ammonium Chloride Solid 
A-2.1.2 Concentrated Nitric Acid.  
A-2.1.3 Dilute Ammonium Hydroxide -Approximately 4 N.  
A-2.1.4 Methyl Red Indicator  - Dissolve 0.1 g of methyl red in 100ml of rectified spirit. 
A-2.1.5 Ammonium Nitrate Solution  — Approximately 2%. 
 
A-2.2 Procedure 
Weigh accurately about 1 g of the prepared sample and dissolve it in 100 ml of water. Filter 
to remove the undissolved matter and wash the filter paper thoroughly. Add 5 g of 
ammonium chloride and 2 drops of concentrated nitric acid to the filtrate “and washings; 
heat to boiling and add dilute ammonium hydroxide, drop by drop, until the solution smells 
faintly of ammonia and shows distinct yellow colour on the addition of two drops of methyl 
red indicator. Boil for 2 rein, filter immediately through filter paper (Whatman No. 40 or 
equivalent) and wash the residue with hot ammonium nitrate solution till the filtrate is free 
from chlorides. Dry the residue and ignite to constant weight at 1100 to 1 2000C in tared 
porcelain or a silica crucible. 
 
A-2.3 Calculation  
Aluminium (as AI 2O3), percent by mass= 100∗ቀ௠
௠ଵቁ−𝐴∗1.4297  
where  
m = mass, in g, of the ignited residue. 
A = percent by mass of iron as determined in Annex B; and 
m1= mass in g of the prepared sample taken for the test. 
 
A-3 Method B (Titration with EDTA  
A-3. 1 Reagents 
A-3. 1.1 Disodium Ethylenediamine Tetra Acetate (EDTA) Solution  — 0.05M. 
Dissolve 18.6125 g of disodium ethylenediamine tetra acetate dihydrate in water and make 
the volume to one Iitre in a volumetric flask. 
 
A-3. 1.2 Concentrated Sulfuric Acid  
A-3. 1.3 Hexamine (Hexamethylene Tetramine)  - Analar 
A-3.1.4 Xylenol Orange Indicator  (Prepare 0.5 percent in water and add 1 to 2 drops of dilute 
sodium hydroxide solution) 
A-3.1.5 Standard Lead Nitrate Solution  0.05 N 
 
 
 
 
 A-3.2 Procedure  CDC 6 (960) DTZS 
 
 
© TBS – All rights reserved 
 Dissolve 5 g of prepared sample in water. Acidify it by adding 1to 2 ml of concentrated 
sulphuric acid and make up the volume to 500 ml in a volumetric flask.Take an aliquot of 50 
ml into a conical flask. Add 50 ml of 0.05 M EDTA solution and heat to just boiling. Cool 
it and add hexamine powder to adjust the pH to 5. Add few drops of xylenol orange indicator. 
Titrate the excess EDTA solution with standard Lead nitrate solution until the colour changes 
from yellow to pink. 
 
A-3.3 Calculation 
Calculate the Aluminium content of the material on the assumption that one millilitre of 0.05 
M EDTA solution is equivalent to 0.002 55 g of Aluminium (as Al 2O3). 
 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 CDC 6 (960) DTZS 
 
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Annex B 
(Normative) 
Determination of Iron 
 
B.1 Apparatus.  
B.1.1 Nessler Cylinders  — 50 ml capacity. 
B.2 Reagents  
B.2.1 Ammonium Persulphate  
B.2.2 Butanolic Potassium Thiocyanate Solution  
Dissolve 10 g of potassium thiocyanate in 10 ml of water. Add sufficient n- butanol to make up 
to 100 ml and shake vigorously till the solution is clear. 
B.2.3 Standard Iron Solution A  
Dissolve 0.702 2 g of ferrous ammonium sulphate  
[FeSO 4·(NH4)2 SO4·6H2O] in 100 ml of water (as per  TZS 59) , add 5 ml of 1: 5 ( v/v) sulphuric 
acid and add dilute solution of potassium permanganate (0.2 percent, m/v) drop wise until a 
slight pink coloration remains after stirring. Dilute with water to 1 000 ml and mix thoroughly. 
One millilitre of this solution contains 0.1 mg of iron as Fe. 
B.2.4 Standard Iron Solution B  
Take 100 ml of the standard iron Solution A ( see B-2.3) and dilute to 1 000 ml with water in a 
1 000 ml volumetric flask. This dilute solution should be prepared fresh. One millilitre of this 
solution contains 0.01 mg of iron (as Fe). 
B.3 PROCEDURE  
B.3.1  
Weigh 50.0 g of the material in a silica dish (capacity – 200 ml) and evaporate it almost to 
dryness over water bath. Dissolve the dry mass in 30 ml water, transfer quantitatively in a 
nessler cylinder of 50 ml capacity, add about 30 mg of ammonium persulphate and 15 ml of 
butanolic potassium thiocyanate solution. Make up to 50 ml, shake vigorously for about 30 s 
and allow the layers to separate. Carry out a control test in another Nessler cylinder using 2 
ml of standard iron Solution B. Compare the intensity of the colour produced in the butanol 
layers in the two cylinders. 
B-3.2 The limit prescribed in Table 1 shall be  taken as not having been exceeded if the 
intensity of colour produced with the material is not greater than that produced in the control 
test. 
 
 
 
 
 
 
 
 
 
 
 
 
  CDC 6 (960) DTZS 
 
 
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Annex C  
(Normative)   
Determination of water-insoluble matter   
  
C.1 Principle  
  
A representative sample of Aluminium Sulfate is dissolved in water. The insoluble matter is 
separated by filtration then dried and weighed.  
  
  
C.2 Apparatus  
  
Ordinary laboratory apparatus and glassware together with the following:  
  
C.2.1 Sintered glass crucible of porosity P40 (pores size between 16 µm to 
40 µm).  
  
C.2.2 Oven capable of being controlled at (105 ± 3) °C.  
  
  
C.3 Procedure  
  
Weigh approximately 10 g of the representative sample (m 4) to the nearest ± 0.01 g and 
dissolve in 1000 ml of water by stirring for 30 min. Then filter the solution under vacuum 
through a dried and weighed glass filter.  After the filtration, wash the residue with 20 ml of 
water and remove excess water by filtering under vacuum.  Dry the residue at (105 ± 3)°C in 
the oven until the mass remains constant and weigh it (m 5) after cooling in a dessicator.  
 
C.4  Expression of results  
  
The insoluble matter expressed as percentage by mass (% (m/m)), C 5 in the product is given 
by the following equation:  
  
                  C 5  =௠ఱ
௠ర 𝑋 100                     
                                        
where   
  
m5 is the mass, in grams, of the residue;  
m4 is the mass, in grams, of the test portion. CDC 6 (960) CD2 
 
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ANNEX D 
(Normative)   
Determination of pH 
 
D-1 Procedure  
Take 5 g of the material and dissolve in 100 ml of freshly boiled and cooled water. Determine 
pH of the solution by means of a suitable pH meter.